Free eats = free food. When you use the words "free food", you have to use them in a sentence for people to understand what you're talking about, such as "there is going to be free food at the party" or "they are giving away free food at the soup kitchen". But when you use "free eats", it's a statement, a sentence of it's own.

Joe: Hey Matt, are you going to the block party?
Matt: No, those people are lame.
Joe: Dude, free eats!
Matt: Oh.....we're SO there!